| In this study, seeds, buds and inflorescence of Alocasia macrorrhiza were used as explants for studying various factors on in vitro culture, and an efficient in vitro regeneration system was established; the rhizome and inflorescence were used as explants for conducting callus induction and plant regeneration; plantlets in vitro were used as materials for finding out the suitable conditions of hydroponics in rooting, pH value and the concentration of nutrient solution.Then the physiological indexes such as chlorophyll contents, protective enzyme activities and MDA contents in hydroponic seedlings under different pH values and nutrient solutions were determined as well. The main resluts were as follows:1 Establishment of in-vitro regeneration system of Alocasia macrorrhizaThe seeds, buds and inflorescence of Alocasia macrorrhiza were used as explants.The in vitro regeneration system was established, and the impact of different factors on in vitro proliferation, rooting and transplanting was also studied. The results showed that the best medium for the proliferation was MS +6- BA 6 mg·L-1 + KT 1.5 mg·L-1 + IBA 0.1 mg·L-1, with proliferation coefficient more than 6.0 and the effect of different types of hormones on in vitro proliferation followed by : 6-BA> KT> IBA> NAA; the optimal concentrations of sugar and agar for proliferation were 30g·L-1 and 5 g·L-1; the impact of different qualities of light on proliferation followed by red> green> blue> white, the chlorophyll content and enzyme activity of plantlets in vitro under the condition of different light qualities were measured, and it was found that the plantlets contained the lowest chlorophyll content, and the highest activity of POD, SOD and CAT under white light, which provided evidence for related physiological basis on the proliferation; the results of different light intensities on the proliferation demonstrated that the most suitable light intensity was 1500 Lx ; the best medium for seedling strengthening and rooting was 1/2MS +1.0 g·L-1AC +2.0 mg·L-1PP333 with strong seedling rate of 82.50%; the best transplanting medium was peat soil combined with vermiculite(3:1)with survival rate of 93%.2 Callus induction and plant regeneration of Alocasia macrorrhizaCallus induction and plant regeneration were preliminarily studied with the rhizome and inflorescence of Alocasia macrorrhiza as explants.The effect of different concentrations and combinations of 2,4-D and KT on rhizome callus induction was studied.The result showed that the best medium for callus induction was MS +2,4-D 0.5 mg·L-1 + KT0.5 mg·L-1 with callus induction rate of 81.67% on average; the most suitable concentrations of 2,4-D and KT for rhizome callus induction were all 0.5 mg·L-1 , the impact of 2,4-D was greater than KT. With young inflorescences of Alocasia macrorrhiza as explants, the effect of different light conditions and the concentrations of 6-BA and NAA on callus induction was studied. The results showed that the concentration of 6-BA too low or too high gone against callus induction, 4 mg·L-1 was appropriate.Compared with the conditions of darkness, low light was more conducive to the promotion of inflorescence callus formation. The rhizome callus of Alocasia macrorrhiza became brown after it was inoculated. Later, new callus formed and differentiated buds on the medium MS+6- BA 6 mg·L-1+KT1.5 mg·L-1+IBA 0.1 mg·L-1. The inflorescence callus of Alocasia macrorrhiza formed with the occurrence of buds. And complete plants regenerated from the inflorescence callus on the callus induction medium as time went by.3 The research in suitable hydroponic conditions of Alocasia macrorrhizaPlantlets in vitro as materials were used for finding out the suitable type and concentration of rooting agent, appropriate pH and concentration of nutrient solution. The results showed that the best rooting agent was 1 mg·L-1 IBA by comprehensive consideration on 4 indicators including the rooting rate, root number, root length and root crude; the appropriate pH value was between 6.0-6.5 by comprehensive consideration on the rooting rate, root number and leaf number of new ones; and by comprehensive consideration on the plant height, stem diameter, leaf length, leaf width and leaf number after hydroponics for 30 days, the most suitable concentration of nutrient solution was 1/2 Hoagland, which was followed by 1/4 Hoagland.4 Studies on physiological changes in hydroponic plantlets of Alocasia macrorrhiza in vitroPlantlets in vitro of Alocasia macrorrhiza as materials were used for finding out the effect of pH value and concentrations of nutrient solution on hydroponic physiological changes. The results showed that the plant chlorophyll content, POD, SOD and CAT enzyme activities were all the highest, while the MDA content was the lowest when the pH value of nutrient solution was 6.0; it appeared the same to the concentration of 1/2 Hoagland nutrient solution, which showed significant difference from the treatments of water control, 1/4 Hoagland and the entire volume of Hoagland nutrient solution. And by comprehensive consideration on morphological respons and physiological changes, the most appropriate pH value was 6.0, while the most suitable concentration of nutrient solution was 1/2 Hoagland.In a word, an efficient regeneration system in vitro of Alocasia macrorrhiza was established in this experiment; callus was induced from the rhizome and buds differentiated, and callus was inducd from the inflorescences and complete plants regenerated; the technical system of hydroponics in Alocasia macrorrhiza was established, which would be of great importance to in vitro multiplication and hydroponics in Alocasia macrorrhiza.
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